Diseased and damaged heart valves pose a serious health problem. Hundreds of thousands of surgeries are performed annually to repair heart valves. The functional properties of heart valves include, but are not limited to, preventing backflow from one chamber to another or between a vessel and a chamber, permitting rapid flow of fluid without imposing resistance on that flow, and withstanding high-pressure loads.
The four heart valves include the tricuspid valve at the exit of the right atrium, the pulmonary valve at the exit of the right ventricle, the mitral valve at the exit of the left atrium, and the aortic valve at the exit of the left ventricle. All four heart valves are generally passive structures that typically do not perform any active contractile function. Each heart valve includes movable leaflets that are designed to open and close in response to differential pressures on either side of the valve. Fluid flows from areas of high pressure to areas of low pressure, and, in the heart, the valves open and close in response to pressure changes. For example, the valves open when pressure in the preceding chamber is higher and close when the pressure in the preceding chamber is lower.
Thus, the valves in the heart help maintain the physiologic direction of fluid flow (e.g., blood flow) via the right atrium-right ventricle-lungs-left atrium-left ventricle-aorta. Although each of these valves has a slightly different structure, they serve similar functions. As stated above, one of those functions is to prevent backflow of fluid. Backflow prevention facilitates the proper direction of flow through the circulatory system and reduces the amount of work the heart must do to pump blood through the system.
There are numerous complications and diseases of the heart valves that can occur. Heart valves may become dysfunctional from inflammation, autoimmune disease, and or calcification. For example, stenosis or hardening of the valve can prevent the valve from fully opening or closing. Therefore, as a result of stenosis, backflow can occur. Consequently, surgery may be necessary to repair or treat damaged or diseased heart valves.